MOST of the current knowledge regarding respiratory disease in rodents is based on the management of laboratory rodents. The emphasis is on diagnosis, elimination and prevention of subclinical respiratory disease rather than treatment. In the author's experience, rats are the most frequently presented small mammals with respiratory problems, followed by guinea pigs and then chinchillas. Animal husbandry, environmental conditions and immune status all play a part in the pathogenesis. While some of the causal bacteria are opportunistic pathogens, other infections are acquired and animals remain infected for life. Therapy usually does not eliminate disease, but only alleviates the symptoms, and it is important that clients are made aware of this. This article provides an overview of common respiratory diseases in pet rodents, with particular emphasis on Mycoplasma and Bordetella species infections.